1. Field of the Invention
This invention relates to a substrate transport apparatus and a substrate transport method which are adapted to transport a substrate, and a recording medium storing a program for performing the substrate transport method.
2. Description of the Related Art
In manufacture of semiconductor devices, various kinds of processing devices are used to process oxidization, diffusion, CVD (chemical vapor deposition), etc. of a substrate, such as a semiconductor wafer. Among such devices, a film deposition apparatus including a vertical type heat-treatment device that can heat-treat a plurality of substrates simultaneously is known.
The film deposition apparatus includes a boat, a lifting/lowering module, and a transfer module (or a substrate transport apparatus). The boat is a substrate holding part that holds a plurality of substrates at predetermined holding intervals in an up/down direction (or a vertical direction), and this substrate holding part is transported to or from a film-deposition container.
The lifting/lowering module is disposed in a loading area under the film-deposition container. When the boat is disposed on an upper part of a lid for enclosing the opening of the film-deposition container, the lifting/lowering module lifts or lowers the lid in the vertical direction so that the boat goes up or down between the film-deposition container and the loading area. The transfer module transfers a substrate between the boat in the loading area and the accommodating container which accommodates the substrates.
Among various film deposition methods using the film deposition apparatus, a method of forming a polyimide film on a surface of a substrate is known. The polyimide film formed on the surface of the substrate can be used as an insulating layer in a semiconductor device. For example, a typical method of forming a polyimide film in which pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA) are used as source material monomers and a polyimide film is formed by vapor deposition polymerization of PMDA and ODA is known.
In order to increase the number of substrates loaded in one boat in the film deposition apparatus of this type, a plurality of stacked members in which each staked member includes two substrates with adjacent back surfaces stacked via a spacer member are held on the boat at predetermined holding intervals in an up/down direction. For example, see Patent Document 1 listed below.
Among the various processing devices for manufacture of semiconductor devices, a substrate transport apparatus is known. In this substrate transport apparatus, when a substrate is transported between an accommodating container for accommodating substrates and a substrate holding part, the substrate is clamped by a stopper member and a clamp unit. For example, see Patent Document 2 listed below.
In the substrate transport apparatus of Patent Document 2, the stopper member is disposed at a front end of a fork to contact the outer edge of the substrate. The clamp unit is disposed on the base end side of the fork to be movable in forward and backward directions. The clamp unit is moved to push the substrate to the stopper member and clamps the substrate with the stopper member.    Patent Document 1: Japanese Laid-Open Patent Publication No. 2009-081259    Patent Document 2: Japanese Laid-Open Patent Publication No. 2009-099918
However, the transfer module (or the substrate transport apparatus) in the film deposition apparatus including the boat holding the stacked members has the following problems.
The substrate and the spacer member, forming the stacked member, have almost the same diameter, but other dimensions of the two elements, such as a thickness, are different from each other. In order to enable the same fork to support both the substrate and the spacer member, it is necessary to provide a substrate supporting module and a spacer-member supporting module in the same fork.
However, if the substrate supporting module and the spacer-member supporting module are arranged on one surface of the fork, the substrate may interfere with the spacer-member supporting module when the substrate is supported by the substrate supporting module. On the other hand, when the spacer member is supported by the spacer-member supporting module, the spacer member may interfere with the substrate supporting module.
Conversely, if the substrate supporting module and the space-member supporting module are arranged on the opposite surfaces of the fork, the thickness of the entire fork is increased and becomes larger than the thickness of the fork in the case in which the substrate supporting module and the spacer-member supporting module are arranged on only one surface of the fork.
During the condition when one substrate or one spacer member is transported between the boat and the accommodating container, to prevent interference between the adjacent substrates or the adjacent spacer members in the up/down direction, the intervals of the substrates or the intervals of the spacer members accommodated in the accommodating container must be enlarged.